Embodiments of the present invention relate generally to a bulb lighting device to monitor patients in a home environment.
Motion sensors are widely used both in public buildings and in private homes. The usage of these sensors is very wide: they can be used to switch on the light, or in security systems. Detecting the movement of elderly people is getting more and more important nowadays. Most people above 65 are living alone at home and in most of the cases they suffer from chronic disease such as Parkinson, Alzheimer or dementia. The highest risk is that they will fall during an everyday activity and there is nobody in the vicinity to help them.
Motion detection in private homes is becoming more and more important. Commercial motion detectors are mainly PIR (Passive Infra-Red) sensors where the radiated heat of the body is detected during motion. Special Fresnel lenses are available for detection at close and far distances and for detection at different heights. One of the main disadvantages of PIR sensors is that they cannot detect stationery objects (e.g. standing person), cannot measure distance, and cannot “look” through even a thin object.
Infrared sensors are widely used, but taking into consideration that in most of the cases a light bulb is covered with an envelope, it makes the passive infrared sensor unusable, Additionally, the heat emitted by the light bulb disturbs the infrared sensor, thus requiring the need of insulation or special alignment. In order to make a device usable in as many conditions as possible, motion detection should be done in the widest range (field of view) as possible. Taking the mentioned heat-disturbance into consideration, it makes the usage of infrared sensor more complicated.
Radar technology is another option to detect motion in a home environment. The radar can “see” through the lamp shield, is not sensitive to radiated heat, can see through thin objects such as curtains etc. and can detect motion in a large field of view.
The term “radar” is generally understood to mean a method by means of which short electromagnetic waves are used to detect distant objects and determine their location and movement. The term RADAR is an acronym for Radio Detection And Ranging.
A complete radar measuring system is comprised of a transmitter with antenna, a transmission path, the reflecting target, a further transmission path (usually identical with the first one), and a receiver with antenna. Two separate antennas may be used, but often just one is used for both transmitting and receiving the radar signal.
Microwaves are generally understood to be electromagnetic waves with frequencies above 2 GHz and wavelengths of less than 15 cm (6 in.). For technical purposes, microwave frequencies are used up to approx. 120 GHz; a limit that will extend upwards as technology advances Far above this limit are to be found the infrared, visible light and ultraviolet ranges.
Microwave frequencies are used intensively for communications and locating purposes. To prevent mutual influence and interference, the use of microwaves is officially regulated. There are, however, also internationally released frequency bands for industrial, scientific and medical purposes (so-called ISM bands). Currently these are the following 4 frequency ranges: 2.45 GHz±50 MHz, 24.125 GHz±125 MHz, 5.8 GHz±75 MHz and 61.25 GHz±250 MHz.
Commonly used radar methods include: CW (Continuous Wave) radar (no distance information), Interferometer radar (disadvantage: the absolute distance information is λ2-periodical), Pulse radar, FMCW (Frequency Modulated Continuous Wave) Reflectometer radar, Combined methods radar and TDR (Time Domain Reflectometry) radar. The basic methods used for radar level measuring equipment are Pulse radar or FMCW radar, sometimes supported by the Interferometer method.
Taking the advantages and disadvantages of the above mentioned methods into consideration, the Pulse radar method meets the present requirements. The principle is very simple: a short electrical pulse or wave package is transmitted, meets the reflector after time t1=a/c and is received back after a total time t2=2a/c, where a is the distance and c is the velocity of light (which is the same as the propagation speed).
The main two disadvantages of both the PIR and radar techniques are: they need wiring, which makes the mounting of these sensors expensive; and they are highly visible, which can make elderly people feel uncomfortable.
Light devices with motion sensing functionality already exist, but the motion sensing is used to turn on the light in these devices.
There are many motion sensors on the market. Most of them use PIR (Passive Infra-Red) for motion sensing. Wireless motion sensors also exist. Wireless as used in relation to these sensors means that they are powered using batteries. There is no such wireless motion sensor known from the prior art where the motion sensor is concealed in a lighting device. From the outside, the device according to the present subject matter, looks like a general light bulb which promotes concealing motion sensors from view. Using radar as the sensing device is also a possible technology for this device.
There are prior documents where radar is used in combination with other sensors, e.g. US Patent Publication No. 2009/0303100 entitled “Motion detection systems using CW radar in combination with additional sensors”. This solution is focusing on reliable motion detection using radar but it is not concealed, or integrated into a light emitting device. It uses wireless technology to transmit a motion signal to a remote station though.
Another group of solutions is focusing on integrating motion sensors into lighting fixtures to switch on light if motion is detected. They all use PIR-based motion detectors: U.S. Pat. No. 5,442,532 entitled “Decorative Lighting Fixture for Motion Detection” or U.S. Pat. No. 5,626,417 entitled “Motion detector assembly for use with a decorative coach lamp” or U.S. Pat. No. 5,814,945 entitled “Lighting fixture control device” or U.S. Pat. No. 6,943,687 entitled “PIR motion detector for a decorative lantern” or U.S. Pat. No. 7,488,941 entitled “Decorative lighting fixture with hidden motion detector”. Most of these solutions are also focusing on hiding the motion detector, but none of them are wireless. U.S. Pat. No. 6,346,705 entitled “Hidden PIR motion detector with mirrored optics” is directly focusing on another possible way of hiding the PIR motion detector.
One of the advantages of using radar technology is that its viewing angle is pretty wide. There is a disclosure of U.S. Pat. No. 6,348,691 entitled “Motion detector with extra-wide angle mirrored optics” in which this kind of motion detector is shown, focusing on achieving a 360 degree viewing angle using PIR detector. This document describes how to achieve this target, but it neither is integrated into a device nor uses wireless technology.
Nowadays, many attempts can be seen to integrate new types of lighting devices or any non-conventional lighting methods into a conventional shape light bulb. The reason of the importance of these attempts is that many customers still prefer, conventional pear-shaped light bulbs. U.S. Pat. No. 6,523,978 entitled “Lamp bulb with stretchable lamp beads therein” shows light beads integrated into a convenient light bulb. One of the aspects of this solution is that the light bulb can be disassembled, thus the shape of the light bead can be adjusted.
There are two ways of communication between a sensor and a remote supervision station, and there are different embodiments to fulfill this requirement, which can be categorized into two main groups: wireless and wired.
The main known wireless communication types (in the 2.4 GHz frequency range) are Bluetooth, WiFi and ZigBee. The first two technologies are known to have high power consumption and, considering that it is desirable to detect motion even if the lamp is switched off, the best choice is to use ZigBee technology specially designed for cases where devices periodically “wake up”, send short messages and then return to a sleep mode.
The device can be battery-powered if the light is off. In this case we cannot use power line communication; the only way is to use wireless communication, preferably ZigBee technology. It is much more secure and it better meets up-to-date requirements.
The ZigBee technology is briefly summarized in the following.
The ZigBee network consists of one coordinator, full function devices (FFD, also known as routers) and reduced function devices (RFD, also known as end devices). The coordinator is unique on the network and only one instance is allowed in one network. Both the FFD and RFD devices can receive and send signals, but the FFD can have child devices, while the FED is on the bottom level (at the end) of the hierarchy. An important requirement of the FFDs is that they need continuous power supply so, in most of the cases, they are plugged into the wall outlet (power line), and batteries are not allowed.
The network topology can be star, mesh or cluster tree. The ZigBee network is best described, among its topology, by the network channel and the network pan ID. Network channel ranges from channel 11 (2405 MHz) to 26 (2480 MHz) and the panID is a unique 16-bit number. Two networks on the same channel with different panID may exist, but is not recommended if there is a free, noiseless channel available.
Networks may further comprise beacon and non-beacon modes. In non-beacon-enabled networks ZigBee Routers typically have their receivers continuously active, requiring a more robust power supply. However, this allows for heterogeneous networks in which some devices receive continuously, while others only transmit when an external stimulus is detected.
In beacon-enabled networks, the ZigBee Routers transmit periodic beacons to confirm their presence to other network nodes. Nodes may sleep between beacons, thus lowering their duty cycle and extending their battery life. Beacon intervals may range from 15.36 milliseconds (at 250 kbit/s) to 786.432 seconds (at 20 kbit/s). However, low duty cycle operation with long beacon intervals requires precise timing, which can conflict with the need for low product cost.
It can be easily seen that it makes sense to use non-beaconed mode. The ZigBee node at the lamp may receive constantly, since it is connected to the mains supply, while a battery-powered light switch would remain asleep until the switch is thrown. The switch then wakes up, sends a command to the lamp, receives an acknowledgment, and returns to sleep. In such a network, the lamp node will be at least a ZigBee Router, if not the ZigBee Coordinator; the switch node is typically a ZigBee End Device.
Wired communication is typically networked over a power line (known as power line communication or power line networking (PLN)) to avoid having additional wires. One must ensure, however, that the power line is not physically isolated. The following options are available. The device may continuously operate on its supply voltage (i.e. does not need batteries) and the lamp switch only sends an on/off signal. The disadvantage of this method is that it is unsafe because of the continuous high voltage supply. Or, one can use this method without having the device continuously on power supply by ensuring that the connection between the lamp and the coordinator is continuous. The disadvantage of this method is that it cannot be implemented in existing circuits, as a conventional lamp switch physically isolates the switched device.
The Power Line Networking is briefly summarized in the following.
The term Power Line Networking is used in many ways: Power Line Communication or Power Line Carrier (both abbreviated as PLC), Power Line Digital Subscriber Line (PDSL), mains communication, power line telecom (PLT), power line networking (PLN), or Broadband over Power Lines (BPL); but they all mean carrying data on a conductor also used for electric power transmission.
One of the many advantages of Power line Communication is that it can be used at every stage of the voltage transmission, at high voltage transmission lines and lower voltages as well. Care must be taken because transformers typically prevent proper signal propagation. Since the power wiring system was originally intended for transmission of AC power, in conventional use, the power wire circuits have only a limited ability to carry higher frequencies. The propagation problem limits the usage of power line communication.
There is also a term for PLN, Homeplug, and there is also an alliance called the HomePlugPower line Alliance, which is a group of electronics manufacturers, service providers, and retailers that establishes standards for, and tests members' devices for, compliance with the various power line communication technologies known as HomePlug.
The speed of the PLNs is comparable to older, common wireless and wired communication systems: HomePlug 1.0 has a data rate of 14 Mbps, HomePNA 2.0 has a data rate of 10 Mbps, while IEEE802.11b has a data rate of 11 Mbps and IEEE802.11a has a data rate of 55 Mbps. For a complete comparison the ZigBee network has a theoretical data rate of 250 kbit/s.
An important parameter of the communication channel is the signal-to-noise ratio, SNR, wherein SNR=(Received power)/(Noise power). The signal clarity is highly affected by the devices (loading impedances) connected to the transmission line (channel). This is the reason why it is still hard to use PLNs over large distances.
There is a need to provide a bulb lighting device with extended functionalities to monitor patients in a home environment, which has a base as a conventional light bulb, and which is capable of replacing the conventional light bulb used in current lighting apparatuses. It can thus be replaced by a conventional light bulb if needed. There is also a need for the ability to communicate between the device and a remote station with minimal additional technical investments.